Page 1
1EE122, Fall ‘05
EECS 122:Introduction to Computer Networks
Course Goals and Overview
Computer Science Division
Department of Electrical Engineering and Computer Sciences
University of California, Berkeley
Berkeley, CA 94720-1776
2EE122, Fall ‘05
Instructors
� Instructor: Ion Stoica ([email protected]) - Office Hours: W 2-3 PM, 645 Soda Hall
� Textbooks- L. L. Peterson and B. Davie, Computer Networks: A System
Approach, 3nd Edition, Morgan Kaufman, San Francisco, 2003.
- W. R. Stevens, B. Fenner, A. M. Rudoff, Unix Network Programming: The Sockets Networking API, Vol. 1, 3rd Ed., Addison-Wesley, Boston, 2004.
3EE122, Fall ‘05
TAs
� Jana Van Gruenen ([email protected])- Discussion section: Th 11-12 299 Cory
� Rowena Luk ([email protected])- Discussion section: Tu 2-3, 299 Cory
� Murali Rangan ([email protected])- Discussion section: F 10-11 299 Cory
� Artur Rivilis ([email protected])- Discussion section: W 1-2, 299 Cory
� Office hours: TBD
4EE122, Fall ‘05
Overview
� Administrivia� Overview and History of the Internet
5EE122, Fall ‘05
Administrivia
� Course Web page: - http://inst.eecs.berkeley.edu/~ee122/- Check often to get the latest information
� Deadlines- HWs: due 3:50 pm on the indicated date (10 minutes
before lecture)� Exams are closed-book, with open crib sheet� Come to office hours, request an appointment,
communicate by e-mail- We are here to help, including general advice!- TAs first line for help with programming problems
� Give us suggestions/complaints as early as possible
6EE122, Fall ‘05
Course Goals
� Learn the main architectural concepts and technological components of communication networks, with the Internet as the overarching example
- Understand how the Internet works
- And why the Internet is the way it is� Apply what you learned in three mini-class projects
Page 2
7EE122, Fall ‘05
Class Workload
� Four homeworks spread over the semester- Strict deadlines and due dates (no slip days!)
� Three (mini-)projects- 1st and 3rd are part of a larger project, which involves
implementing a comprehensive network application
• C (or C++) required
- 2nd is a simulation project � One midterm exams
- October 17� Final exam
- December 17
- Note dates and plan your travel accordingly!
8EE122, Fall ‘05
Grading
� Consultation on HWs is OK, but must hand in own work- Correlation between understanding HWs and doing well on exams
� Course graded to mean of B- Relatively easy to get a B, harder to get an A or a C- 10% A, 15% A-, 15% B+, 20% B, 15% B-, 15% C+, 10% C- A+ reserved for superstars (only 1 or 2 per class)- Mean can shift up for an especially great class
20%Final exam
20%Midterm exam
40%
(10% + 10% + 20%)
Projects
20%
(5% each)
Homeworks
9EE122, Fall ‘05
Overview
� Administrivia� Overview and History of the Internet
• See http://www.isoc.org/internet/history/ for more details
10EE122, Fall ‘05
What do this two have in Common?
� First printing press� Key idea: splitting up text in
individual components- E.g., lower, upper case letters
� Bible: first mass produced book
Johann Gutenberg(1398-1468)
The Internet
Both lower the cost of distributing information Both lower the cost of distributing information
11EE122, Fall ‘05
What is a Communication Network?(End-system Centric View)
� Network offers one basic service: move information- Bird, fire, messenger, truck, telegraph, telephone, Internet …- Another example, transportation service: move objects
• Horse, train, truck, airplane ...� What distinguish different types of networks?
- The services they provide� What distinguish the services?
- Latency- Bandwidth- Loss rate- Number of end systems- Service interface (how to invoke the service?)- Others
• Reliability, unicast vs. multicast, real-time...
12EE122, Fall ‘05
What is a Communication Network?(Infrastructure Centric View)
� Communication medium: electron, photon� Network components:
- Links – carry bits from one place to another (or maybe multiple places): fiber, copper, satellite, …
- Interfaces – attach devices to links
- Switches/routers – interconnect links: electronic/optic, crossbar/Banyan
- Hosts – communication endpoints: workstations, PDAs, cell phones, toasters
� Protocols – rules governing communication between nodes- TCP/IP, ATM, MPLS, SONET, Ethernet, X.25
� Applications: Web browser, X Windows, FTP, ...
Page 3
13EE122, Fall ‘05
Network Components (Examples)
��� ����� �
���� �� ���������� �
Links Interfaces Switches/routers��� ����� ����������� �
��� � ��� ����������� �
����� ����� � �� ���
!"��� ��#��������%$&� � �'�
14EE122, Fall ‘05
Types of Networks
� Geographical distance- Local Area Networks (LAN): Ethernet, Token ring, FDDI- Metropolitan Area Networks (MAN): DQDB, SMDS- Wide Area Networks (WAN): X.25, ATM, frame relay- Caveat: LAN, MAN, WAN may mean different things
• Service, network technology, networks� Information type
- Data networks vs. telecommunication networks� Application type
- Special purpose networks: airline reservation network, banking network, credit card network, telephony
- General purpose network: Internet
15EE122, Fall ‘05
Types of Networks
� Right to use- Private: enterprise networks- Public: telephony network, Internet
� Ownership of protocols- Proprietary: IBM System Network Architecture (SNA)- Open: Internet Protocol (IP)
� Technologies- Terrestrial vs. satellite- Wired vs. wireless
� Protocols- IP, AppleTalk, SNA
16EE122, Fall ‘05
The Internet (cont’d)
� Global scale, general purpose, heterogeneous-technologies, public, computer network
� Internet Protocol- Open standard: Internet Engineering Task Force (IETF) as
standard body ( http://www.ietf.org )
- Technical basis for other types of networks
• Intranet: enterprise IP network� Developed by the research community
17EE122, Fall ‘05
Services Provided by the Internet� Shared access to computing resources
- telnet (1970’s)� Shared access to data/files
- FTP, NFS, AFS (1980’s)� Communication medium over which people interact
- email (1980’s), on-line chat rooms, instant messaging (1990’s)- audio, video (1990’s, early 00’s)
• replacing telephone network?� Medium for information dissemination
- USENET (1980’s)- WWW (1990’s)
• replacing newspaper, magazine?- Audio, video (late 90’s, early 00’s)
• replacing radio, TV?- File sharing (late 90’s, early 00’s)
18EE122, Fall ‘05
Growth of the Internet
Number of Hosts on the Internet:Aug. 1981 213Oct. 1984 1,024Dec. 1987 28,174 Oct. 1990 313,000
Oct. 1993 2,056,000Apr. 1995 5,706,000Jan. 1997 16,146,000Jan. 1999 56,218,000Jan. 2001 109,374,000
Jan. 2003 171,638,297Jan. 2005 317,646,084
1
10
100
1000
10000
100000
1000000
10000000
100000000
1000000000
1981 1985 1989 1993 1997 2001
Data available at: http://www.isc.org/
Estimated number of users: http://www.internetworldstats.com/stats.htm
Page 4
19EE122, Fall ‘05
Internet vs. Telephone Net
� Strengths
- Intelligence at ends
- Decentralized control
- Operates over heterogeneous access technologies
� Weaknesses
- No differential service
- Variable performance delay - New functions difficult to add
since end nodes must be upgraded
- No trusted infrastructure
� Strengths
- No end-point intelligence
- Excellent voice performance� Weaknesses
- Achieves performance byoverprovisioning resources
- Difficult to add new services to “Intelligent Network” due to complex call model
- Expensive approach for reliability
Internet: “intelligent” edge, “dump” core
Internet: “intelligent” edge, “dump” core
Telephone Net: “dump” edge, “intelligent” core
Telephone Net: “dump” edge, “intelligent” core
20EE122, Fall ‘05
History of the Internet
� 68-70’s: started as a research project, 56 kbps, initially 4 nodes (UCLA, UCSB, SRI, Utah) then < 100 computers
- http://www.cnn.com/2004/TECH/internet/08/29/internet.birthday.ap/index.html
� 80-83: TCP/IP, DNS; ARPANET and MILNET split � 85-86: NSF builds NSFNET as backbone, links 6
Supercomputer centers, 1.5 Mbps, 10,000 computers� 87-90: link regional networks, NSI (NASA), ESNet (DOE),
DARTnet, TWBNet (DARPA), 100,000 computers� 90-92: NSFNET moves to 45 Mbps, 16 mid-level networks� 94: NSF backbone dismantled, multiple private backbones;
Introduction of Commercial Internet� Today: backbones run at 10 Gbps, close to 200 millions
computers in 150 countries
21EE122, Fall ‘05
The ARPANet
� Paul Baran- RAND Corp, early 1960s
- Communications networks that would survive a major enemy attack
� ARPANet: Research vehicle for “Resource Sharing Computer Networks”
- 2 September 1969: UCLA first node on the ARPANet
- December 1969: 4 nodes connected by phone lines
����������
� ������ �������
����������������
� !��"# $�#&% �� �'# (
)�)�*,+.-�/ 01+�2�/ +43 045�6 -�07-98�+�-�:+.2�-;3 8�+.-�<.= /�> -?0@-�A�A�/�B -C5�<.D�>�-�A�A�D�<
22EE122, Fall ‘05
ARPANet Evolves into Internet
EGF H4I�J�(K �� L���4M�N �� O9N F7����#�(�9LP !F�Q.L.F� SRT���.U�V H�J.L.F�9LP !F�Q.L.F� �W�X�U�"���L��.F�(
��O�O�N � U.�! �� J�L@I�JS(Y �� L������# Z���O�O9N � U.�! �� J�L@��F�QP[�� U.F@#�QSJ\[�� ] F�Q��� # Z���O�O�N � US�P �� J�L�� L.^.Q!��(Y !Q!M�U. !M�Q!F#�Q.J.[�� ]�F�Q�_ F�`KU�J�����F�QPU.F@ SJ�J�Va� Sb�F\ !U\c d
����#���e�F. ����fge�F. #���e�F\
f� #�h!��#ie���j�e�F. k$�F�Q!F��.M�N �P �� J�L7l�J�����F�Q!U�� ��N � m��P �� J�L
% ���9n % ���9n % ��o�n % ����n R�����nEGEGE
�9��#����#��� #
����fge�F. SZ����\ !F�N � !F4L.F. !p�J.Q.V#���e�F. SZ����.]�� J@e�F. !p�J.QSV
23EE122, Fall ‘05
24EE122, Fall ‘05
Page 5
25EE122, Fall ‘05
26EE122, Fall ‘05
Parallel Backbones
����������� ����������������������������� �!�#"$&%('���)*�+�����,�-�.���/10324������ 56�����7�3�-5���%8��'����������������
27EE122, Fall ‘05
Network “ Cloud”
28EE122, Fall ‘05
9;:=<;> ?A@8BDCE�:AF
Regional Nets + Backbone
9;:=<;> ?G@8BDCE�:AF 9;:=<;> ?G@8BDC
E�:AF
9;:=<;> ?A@8BDCE�:AF 9;:=<;> ?G@8BDC
E�:AF9;:=<;> ?G@8BDCE�:AF
H=BJIAKGLM?=@8:
����e ����e����e
����e7Z�� J.U.��NS��Q!F�� e�F� !p�J.Q.V
29EE122, Fall ‘05
N=OQP
Backbones + NAPs + ISPs
NROQP
N=OSPN=OQP
HDT8U=> @J:AUVUN=OSP W ?=@JUJTAXY:DZN=OQP
����e ����e����e
e���# e��g#H=B8IGKAL=?=@8:AU
$�� ��N `KM�O
�9��# Z\� LP !F�Q.L.F� ���F�QP[ � U.F@#�Q.J.[�� ]�Fe���# Z e�F. !p�J.Q.V@��U.USF�(S(�#�J�� LS
30EE122, Fall ‘05
W ?=Z[:E�:AFV\]?=ZVKVU
W ?A^JBA_
Core Networks + Access Networks
`�a ?=Xb:
NROQPW > @8<=T;C BAZ
ObcJZ8> @8F dQe�f
����e ����e����e
e���#
$�� ��N `KM\O
$�����7N p��hg (�J.L
e���#
���H�N FI�F��.]&W�L.]9(
�F�N N�F�N N
FaN N
���P !F�N N � !Fj�� X�F�]4E � Q!F�N F (P(
Page 6
31EE122, Fall ‘05
W ?A^JBA_
Computers Inside the Core
`�a ?=Xb:
N=OQPW > @8<=T;C BAZ
ObcJZ8> @8F dQe�f
����e ����e����e
e���#
$�� ��N `KM�O
$g�����N p��hg (�J.L
e���#
��\HaN FI�F��.] W�L\]9(
�F�N N�F�N N
F�N N
���P !F�N N � !Fj�� X F�]4E � QPF�N F (!(
32EE122, Fall ‘05
The Evolution of the Enterprise
#�Q�� [.�P !F@�J.QSO�J\Q!�. !Fe�F. !p�J.Q.V
$�F�]�� U.�P !F�]&^S�.U�� N � �� F (PhU�J���O.MP SF�Q�U.F L. !F�QS(
$�F�]�� U.�P !F�]&�\O�O�N � U.�P �� J�L�(Ph��QP] O.�.QP g $���� �W�c ��c b��7Q!�.U�N F
f BJFV:��������=U�9LS !F�QSL.��N.M�(!F�QS(
��� �7� !F�]4U�M\(Y SJ���F QPhF�X� !F�QSL.��N.�SU.U.F (.(
33EE122, Fall ‘05
The Evolution of the Enterprise
#�Q�� [.�P !F@�J.QSO�J\Q!�. !Fe�F. !p�J.Q.V
$�F�]�� U.�P !F�]&^S�.U�� N � �� F (PhU�J���O.MP SF�Q�U.F L. !F�QS(
�7M. S(.J.M.Q!U.F�] KW�LP !F�Q.O.Q�� (PF@��F (.J.M.Q!U.F
#�N �SL�L�� L.������O�O�(F c ��c b.#�F J�O�N F ��J.^P
��������9LS !F�QSL.��N.M�(!F�QS(
��� �7� !F�]4U�M\(Y SJ���F QPhF�X� !F�QSL.��N.�SU.U.F (.(
34EE122, Fall ‘05
The Evolution of the Enterprise
�7M. S(.J.M.Q!U.F�]EGF�H4I�J�(Y �� L��
$�F�]�� US�P !F�]?j��.U�� N � g��M. S(.J.M.QPUSF�]W���#@��O�O.(
���������LP !F�QSL\� N.M�(PF�QS(
�9LP !F�Q.L.F�
W�X� !F�QSL.��N. M�(P SJ���F�QS(
��� QK !M.��NS#�Q�� [.�! !F4e�F� !p�J\QSV����#@�'F (!"
35EE122, Fall ‘05
The Evolution of the Enterprise
��M. S(.J.M.QPUSF�]EGF H4I�J�(Y �� L�� $�F�]�� US�P !F�]?j��.U�� N � g
��M. S(.J.M.QPUSF�]W���#@��O�O.(
���������LP !F�QSL\� N.M�(PF�QS(
�9LP !F�Q.L.F�
W�X� !F�QSL.��N. M�(P SJ���F�QS(
��� QK !M.��NS#�Q�� [.�! !F4e�F� !p�J\QSV�9��#�'F (."
�9LP !F�QSL.F� ��F�QP[�� U.F (
��F��.QPU\"��.U�"�� L����]�(W��J����
����� �
36EE122, Fall ‘05
The Evolution of the Enterprise
������� � �!#"�� $&%�'(*)&+-,�� �)�.&+�$#,�� /�)�+
0�1�1�1
2�3�'4"�$�5�)�+�'
26$�%#"-)�%#"�7*)8� � ,�)�+49;: <�)�"�=
>�+#/;.�!�+?"?9@�!� �� � � "�� )�'�ACB�5D"
2�!� �E6� %�BGFAH)�/D� !�(D)�+-,�)�+�'
IJ%#"-)&+�%�)&"(D)�+#,�� �)�'
(D)�!�+# KE2�!� �E�)�L/6'M�26$�5�5
N�3�"�'�$�3�+# �)&/OP)�Q;R�$�'4"�� %&B
����� �
IJ(D.�A;)�'#E
S8.�<�'
Page 7
37EE122, Fall ‘05
Services Within the Network: Content Distribution
������������ ��.�!�+-!�� � )��K<�)�"���$�+�����!� ���Q�$�%�)�'IJ%#"-)&+�%�)&"�M��� �E&!K%&B�)�.�$&� %#"�'
����������� �"!�# ��$
(* �!�� !�Q6� );(D)�+-,�)�+�'
%&('���"� ���
38EE122, Fall ‘05
P2P Services in the Internet:Napster, Gnutella, BitTorent, …
)*)+)26$�� /J�&� !#9 (L��)�)�/$�, (D$�3�%�/��+&� "�%K)�9C(L��)�!�+�' 2*� %�/�)�+#)6� � !
)*)+)
- # . �"!/��.+0 �1 .�2�# �
3��4 # � ! .65708�"��9+0: # $�;85 ���"��9*0
������< � .
= . # ;8� ��5�9"> !�# $ 4�?��� ��. # $ 4 . �� ��>�.�� @�"A/ $ � '1B # $ 4 �"� B B � ' ��.��"!�# ��$
C �!K%�Q&)�/D� '4"-+&� Q&3�"-)�/!� �+�$�'�' ��)�)�+�'�D
39EE122, Fall ‘05
Summary
E Course administrative triviaE Internet history and background